/**
* Called when the client provides the multi-sig contract. Checks that the previously-provided
* refund transaction spends this transaction (because we will use it as a base to create payment
* transactions) as well as output value and form (ie it is a 2-of-2 multisig to the correct
* keys).
*
* @param multisigContract The provided multisig contract. Do not mutate this object after this
* call.
* @return A future which completes when the provided multisig contract successfully broadcasts,
* or throws if the broadcast fails for some reason Note that if the network simply rejects
* the transaction, this future will never complete, a timeout should be used.
* @throws VerificationException If the provided multisig contract is not well-formed or does not
* meet previously-specified parameters
*/
public synchronized ListenableFuture<PaymentChannelServerState> provideMultiSigContract(
final Transaction multisigContract) throws VerificationException {
checkNotNull(multisigContract);
checkState(state == State.WAITING_FOR_MULTISIG_CONTRACT);
try {
multisigContract.verify();
this.multisigContract = multisigContract;
this.multisigScript = multisigContract.getOutput(0).getScriptPubKey();
// Check that multisigContract's first output is a 2-of-2 multisig to the correct pubkeys in
// the correct order
final Script expectedScript =
ScriptBuilder.createMultiSigOutputScript(2, Lists.newArrayList(clientKey, serverKey));
if (!Arrays.equals(multisigScript.getProgram(), expectedScript.getProgram()))
throw new VerificationException(
"Multisig contract's first output was not a standard 2-of-2 multisig to client and server in that order.");
this.totalValue = multisigContract.getOutput(0).getValue();
if (this.totalValue.signum() <= 0)
throw new VerificationException(
"Not accepting an attempt to open a contract with zero value.");
} catch (VerificationException e) {
// We couldn't parse the multisig transaction or its output.
log.error("Provided multisig contract did not verify: {}", multisigContract.toString());
throw e;
}
log.info("Broadcasting multisig contract: {}", multisigContract);
state = State.WAITING_FOR_MULTISIG_ACCEPTANCE;
final SettableFuture<PaymentChannelServerState> future = SettableFuture.create();
Futures.addCallback(
broadcaster.broadcastTransaction(multisigContract).future(),
new FutureCallback<Transaction>() {
@Override
public void onSuccess(Transaction transaction) {
log.info(
"Successfully broadcast multisig contract {}. Channel now open.",
transaction.getHashAsString());
try {
// Manually add the multisigContract to the wallet, overriding the isRelevant checks
// so we can track
// it and check for double-spends later
wallet.receivePending(multisigContract, null, true);
} catch (VerificationException e) {
throw new RuntimeException(
e); // Cannot happen, we already called multisigContract.verify()
}
state = State.READY;
future.set(PaymentChannelServerState.this);
}
@Override
public void onFailure(Throwable throwable) {
// Couldn't broadcast the transaction for some reason.
log.error("Broadcast multisig contract failed", throwable);
state = State.ERROR;
future.setException(throwable);
}
});
return future;
}
/**
* Closes this channel and broadcasts the highest value payment transaction on the network.
*
* <p>This will set the state to {@link State#CLOSED} if the transaction is successfully broadcast
* on the network. If we fail to broadcast for some reason, the state is set to {@link
* State#ERROR}.
*
* <p>If the current state is before {@link State#READY} (ie we have not finished initializing the
* channel), we simply set the state to {@link State#CLOSED} and let the client handle getting its
* refund transaction confirmed.
*
* @return a future which completes when the provided multisig contract successfully broadcasts,
* or throws if the broadcast fails for some reason. Note that if the network simply rejects
* the transaction, this future will never complete, a timeout should be used.
* @throws InsufficientMoneyException If the payment tx would have cost more in fees to spend than
* it is worth.
*/
public synchronized ListenableFuture<Transaction> close() throws InsufficientMoneyException {
if (storedServerChannel != null) {
StoredServerChannel temp = storedServerChannel;
storedServerChannel = null;
StoredPaymentChannelServerStates channels =
(StoredPaymentChannelServerStates)
wallet.getExtensions().get(StoredPaymentChannelServerStates.EXTENSION_ID);
channels.closeChannel(
temp); // May call this method again for us (if it wasn't the original caller)
if (state.compareTo(State.CLOSING) >= 0) return closedFuture;
}
if (state.ordinal() < State.READY.ordinal()) {
log.error("Attempt to settle channel in state " + state);
state = State.CLOSED;
closedFuture.set(null);
return closedFuture;
}
if (state != State.READY) {
// TODO: What is this codepath for?
log.warn("Failed attempt to settle a channel in state " + state);
return closedFuture;
}
Transaction tx = null;
try {
Wallet.SendRequest req = makeUnsignedChannelContract(bestValueToMe);
tx = req.tx;
// Provide a throwaway signature so that completeTx won't complain out about unsigned inputs
// it doesn't
// know how to sign. Note that this signature does actually have to be valid, so we can't use
// a dummy
// signature to save time, because otherwise completeTx will try to re-sign it to make it
// valid and then
// die. We could probably add features to the SendRequest API to make this a bit more
// efficient.
signMultisigInput(tx, Transaction.SigHash.NONE, true);
// Let wallet handle adding additional inputs/fee as necessary.
req.shuffleOutputs = false;
req.missingSigsMode = Wallet.MissingSigsMode.USE_DUMMY_SIG;
wallet.completeTx(req); // TODO: Fix things so shuffling is usable.
feePaidForPayment = req.tx.getFee();
log.info("Calculated fee is {}", feePaidForPayment);
if (feePaidForPayment.compareTo(bestValueToMe) > 0) {
final String msg =
String.format(
Locale.US,
"Had to pay more in fees (%s) than the channel was worth (%s)",
feePaidForPayment,
bestValueToMe);
throw new InsufficientMoneyException(feePaidForPayment.subtract(bestValueToMe), msg);
}
// Now really sign the multisig input.
signMultisigInput(tx, Transaction.SigHash.ALL, false);
// Some checks that shouldn't be necessary but it can't hurt to check.
tx.verify(); // Sanity check syntax.
for (TransactionInput input : tx.getInputs())
input.verify(); // Run scripts and ensure it is valid.
} catch (InsufficientMoneyException e) {
throw e; // Don't fall through.
} catch (Exception e) {
log.error(
"Could not verify self-built tx\nMULTISIG {}\nCLOSE {}",
multisigContract,
tx != null ? tx : "");
throw new RuntimeException(e); // Should never happen.
}
state = State.CLOSING;
log.info("Closing channel, broadcasting tx {}", tx);
// The act of broadcasting the transaction will add it to the wallet.
ListenableFuture<Transaction> future = broadcaster.broadcastTransaction(tx).future();
Futures.addCallback(
future,
new FutureCallback<Transaction>() {
@Override
public void onSuccess(Transaction transaction) {
log.info("TX {} propagated, channel successfully closed.", transaction.getHash());
state = State.CLOSED;
closedFuture.set(transaction);
}
@Override
public void onFailure(Throwable throwable) {
log.error("Failed to settle channel, could not broadcast", throwable);
state = State.ERROR;
closedFuture.setException(throwable);
}
});
return closedFuture;
}